Assessment and determination of the most suitable drought resistance index for figures and advanced lines of bread wheat

In order to study the effect of drought stress on quantitative attributes of 40 figures and lines, bread wheat was tested in two environments, normal and drought stress. The experiment was designed in perfect random blocks and executed in 3 replications at the Agricultural Research Center and Natural Resource of Tehran Province in the agricultural year 2008-2009. Results of the variance analysis showed that for both normal and drought stress conditions, differences among the genotypes, in terms of most characteristics were significant. Correlations between different drought resistance indexes and grain yield from both normal and stress conditions were positive and significant. However, correlations of SSI and TOL indexes with yield in normal condition were positive and significant but results were negative and significant with yield in stress condition. Calculations done with the various drought resistance indexes indicated that 3 indexes; those of Mean Productivity (MP), Geometrical Mean (GMP) and Stress Tolerance Index (STI) were the most important indexes for the identification of a genotype’s resistance to drought. From the results of the By Plot diagram and the values placed on the genotype resistance indexes, numbers 39 (ws-82-9), 38 (DN-11), and 32 with pedigree (CHEN/AGLOPS/ …) was found as the most likely and Gaspard figure and the line no.8 with pedigree (GASPARD/ALD//"s"/snb/"s"/3/) and line no.3 with pedigree (M-75-10) was found to be the most sensitive genotype to drought stress.